1. Field of the Invention
The present invention relates to a semiconductor device in which a barrier insulating film is formed over wiring of a copper film or mainly copper film on a substrate, and a method of manufacturing the same.
2. Description of the Prior Art
In recent years, not only a higher degree of integration of semiconductor integrated circuit devices, but also a higher data transfer rate has been demanded. For this reason, there is a need for a barrier insulating film for wiring of copper film or mainly copper film, which has a copper diffusion preventing capability and a low relative dielectric constant.
As the barrier insulating film, either a silicon oxide film formed by a plasma CVD method using a film-forming gas that contains tetramethylsilane (SiH(CH3)4) and CH4 or a silicon nitride film formed by the plasma CVD method is employed.
However, there is the problem with the silicon oxide film, that while the relative dielectric constant is low, it contains a large amount of carbon and thus it is difficult to sufficiently suppress the leakage current. Also, there is the problem that the copper diffusion preventing capability of the silicon oxide film is not sufficient. In contrast, there is the problem with a silicon nitride that, while the leakage current is low and the diffusion preventing capability with respect to the copper is sufficiently high, the relative dielectric constant is large.
It is an object of the present invention to provide a semiconductor device having a barrier insulating film which covers the wiring made of copper film or mainly copper film, whose leakage current is low, whose copper diffusion preventing capability is sufficiently high, and whose relative dielectric constant is small, and a method of manufacturing the same.
An insulating film that contains silicon, oxygen, nitrogen, and hydrogen or silicon, oxygen, nitrogen, hydrogen, and carbon is dense, its leakage current is low, and its copper diffusion preventing capability is sufficiently high, but its relative dielectric constant is higher because of its nitrogen content. Also, the selective etching ratio of the insulating film to the SiO2 film formed by the plasma CVD method is large. In contrast, in an insulating film that contains either silicon, oxygen, and hydrogen or silicon, oxygen, hydrogen, and carbon, the relative dielectric constant is lower, but the denseness is relatively lower and thus the leakage current is large. Also, such an insulating film has insufficient copper diffusion preventing capability.
In the present invention, the barrier insulating film for covering the wiring made of copper film or mainly of copper film has a two or more a layered structure including at least a first barrier insulating film and a second barrier insulating film. The first barrier insulating film contains either silicon, oxygen, nitrogen, and hydrogen or silicon, oxygen, nitrogen, hydrogen, and carbon. The second barrier insulating film contains silicon, oxygen, and hydrogen or silicon, oxygen, hydrogen, and carbon. Either the first barrier insulating film or the second barrier insulating film may be formed as the layer that comes into contact with the wiring of the copper film or mainly copper film.
More particularly, in order not to adversely affect low leakage current and the high diffusion preventing capability with respect to the copper, the first barrier insulating film that has the relatively high relative dielectric constant is made thin, while the second barrier insulating film that has the low relative dielectric constant is made sufficiently thick to provide the overall film thickness necessary for the barrier insulating film. As a result, the barrier insulating film composed of at least the first barrier insulating film and the second barrier insulating film together provide a relatively low dielectric constant, a low leakage current, and a sufficiently high copper diffusion preventing capability.
A first barrier insulating film containing silicon, oxygen, nitrogen, and hydrogen can be formed by plasmanizing a first film-forming gas containing silane (SiH4), at least one of N2O and H2O, and at least one of N2 and NH3 for reaction. Also, a first barrier insulating film that contains silicon, oxygen, nitrogen, hydrogen, and carbon can be formed by plasmanizing a first film-forming gas containing at least one of siloxane and methylsilane (SiHn(CH3)4-n:n=0, 1, 2, 3), at least one of N2O, H2O and CO2, and at least one of N2 and NH3 to react.
A second barrier insulating film which contains silicon, oxygen, and hydrogen can be formed by plasmanizing a second film-forming gas containing silane and at least one of N2O and H2O for reaction. A second barrier insulating film which contains silicon, oxygen, hydrogen, and carbon can be formed by plasmanizing a second film-forming gas containing at least one of siloxane and methylsilane (SiHn(CH3)4-n:n=0, 1, 2, 3), and at least one of N2O, H2O and CO2 for reaction.
In addition, an insulating film having a low dielectric constant may be further formed on the above barrier insulating film. In this case, the barrier insulating film and the insulating film having the low dielectric constant may be employed as the interlayer insulating film by forming new wiring made of a copper film or mainly copper film on the insulating film having the low dielectric constant.